Pharmacokinetics of alkylresorcinol metabolites in human urine

Abstract

Wholegrain cereals are reported to promote beneficial health effects. Wholegrain wheat and rye are almost exclusive sources of alkylresorcinols, and intact alkylresorcinols together with their plasma and urinary metabolites, 3-(3,5-dihydroxyphenyl)-1-propanoic acid (DHPPA) and 3,5-dihydroxybenzoic acid (DHBA), have been proposed as biomarkers of the intake of these foods in humans. The pharmacokinetics of alkylresorcinols and their metabolites in plasma have been determined but not that of the urinary metabolites. We aimed to characterise the urinary pharmacokinetics of alkylresorcinol metabolites in humans to evaluate their potential as biomarkers of wholegrain wheat and rye. A group of fifteen volunteers followed a low-alkylresorcinol diet for 2d before ingesting a single dose of rye bread, containing 100mg alkylresorcinols. Urine was collected between baseline (0h) and 25h after administration. Thereafter alkylresorcinol metabolites were quantified by HPLC with coulometric electrode array detection. Maximum excretion rates were observed at 5-6h for both metabolites, DHPPA being predominant over DHBA and also possessing a greater area under the curve 0-25h. Total urinary recovery between 0 and 25h yielded 43% of ingested alkylresorcinols, and at 25h significant amounts of metabolites were still retained in the body, suggesting that even a spot urine sample may be sufficient to indicate whether or not wholegrain wheat or rye is a daily dietary component. These results support the use of urinary DHPPA and DHBA as biomarkers of wholegrain wheat and rye and enable new potential for studying the association between wholegrain intake and diseases, even in the absence of dietary data. Copyright © The Authors 2011.